Very short-duration, high-power laser pulses are needed for some applications. Such pulses may have a duration in the tens of femtoseconds. However, it may be risky to attempt to amplify such short-duration pulses, because the gain medium may be damaged due to the high peak field and energy densities of the short-duration pulse.
One strategy to amplify short-duration optical pulses is to broaden (i.e., expand) the pulse to a longer duration, for example in the picosecond range. The amplification is performed on the longer-duration pulse, which has a lower energy density than the shorter-duration pulse. Because of the lower energy density of the longer-duration pulse, there is less likelihood of damage to the gain medium of the amplifier. The amplified pulse is then compressed back to the required shorter duration, for example in the tens of femtoseconds range.
The implementation of this amplification strategy requires optical transformations of the light pulse using appropriate hardware. A limiting factor on this amplification strategy is aberrations of various types introduced into the light pulse by the pulse broadening and pulse compression hardware. The aberrations have the net effect of lengthening the minimum pulse duration or, stated alternatively, of placing a limit on the minimum duration of the amplified light pulse. That is, the temporally broadened, amplified, and then temporally compressed light pulse is necessarily longer in time than the original unamplified light pulse.
There is a need for an improved approach to broadening and/or compressing short-duration light pulses, which avoids the limitations placed on the temporal compression by aberration effects. The present invention fulfills this need, and further provides related advantages.